The present invention relates to the use of hydraulic fracturing to provide subterranean well linkage and more particularly, to the enhancement of such fracturing by use of cold injected fluids.
In certain circumstances, it is desirable to provide subterranean communication between boreholes in the earth. For example, in the case of a well blowout, an offset well is often provided for injection of drilling mud or other kill fluids into the blowout well. Ideally, the offset well is directionally drilled to actually intersect the blowout well. In practice, such direct intersection is rare. Communication between the offset injection well and the blowout well is often provided by use of hydraulic fracturing. However, in many cases, the fractures generated in the injection well do not intersect the blowout well. The fractures tend to propagate along naturally occuring areas of low stress which may or may not intersect the blowout well.
There are also a number of other circumstances in which subterranean links between boreholes are necessary. These include in-situ shale retorting, underground coal gasification and enhanced oil recovery fireflood processes. In each such case, a hydraulically induced fracture can, under the proper circumstances, provide the required link. However, as described above, the direction in which a fracture will travel is usually not controllable and often not even predictable.